Conestoga College Fire Safety OHS8035 PDF

FIRE SAFETY OHS8035 Hazard Identification www.conestogac.on.ca/ce  Content Part 1: Fire Safety Awareness Part 2: Storage and Dispensing of Flammable Liquids Part 3: Hazards related to Dust and Vapours Workplace Fire Hazards 3 Wo...

FIRE SAFETY OHS8035 Hazard Identification www.conestogac.on.ca/ce  Content Part 1: Fire Safety Awareness Part 2: Storage and Dispensing of Flammable Liquids Part 3: Hazards related to Dust and Vapours Workplace Fire Hazards 3 Workplace Fire Hazards What is the fire triangle? oxygen, heat, fuel Which class of extinguisher contains water Class A What is unique about Class C fire extinguisher? Non conductive for electrical fires Such as carbon dioxide 4  THE NATURE OF FIRE Fire is a chemical reaction known as combustion. In simple scientific terms it is the rapid oxidation of combustible material which releases energy in the form of light and heat. Geometrically it is represented by a triangular pyramid known as the fire tetrahedron, the four sides being representative of heat, oxygen, fuel and the chemical chain reaction.  Fire Tetrahedron A source of heat is required in order for ignition to occur A fire cannot ignite unless it has a certain amount of heat, and it cannot grow without heat Different materials have different ‘flash points’ e.g. the lowest temperature at which they ignite Combustion reactions also produce heat as they burn, further increasing the temperature of the fuel  Fire Tetrahedron A source of fuel is required in order for ignition to occur Fire cannot start if there isn’t any material available to burn. Businesses and homes alike are full of flammable materials including fabrics, wood, oil, and paper. Fuel is probably the hardest ‘side’ of the fire triangle you can remove  Fire Tetrahedron A fire needs oxygen to start and continue To sustain the combustion reaction, oxygen reacts with the burning fuel to release heat and CO2 Fire blankets and certain fire extinguishers remove the oxygen ‘side’ of the triangle by removing it or displacing it, causing suffocation and thereby ceasing the combustion reaction  Fire Tetrahedron Fires involving metals such as titanium, lithium and magnesium have a chemical reaction that requires a different approach for suppression This is a Class D fire Water will exacerbate the combustion Requires inert agents like sand to smother it  THE CAUSES OF FIRE Generally, a fire will only occur with the right mixture of three elements: a source of fuel, oxygen and a source of ignition (heat). To stop the fire one of these three elements must be removed from equation  What causes fire? Most work environments have various sources of flammable and combustible materials and also potentially many sources of possible ignition Here are just some examples of sources of ignition: ELECTRICAL HAZARDS Wires, machinery, sparks FRICTION Rollers, pulleys, conveyors OPEN FLAMES Welding equipment, furnaces HEATING DEVICES Floor or wall mounted heaters SMOKING Matches/cigarette butts MECHANICAL SPARKS Equipment and machinery CHEMICALS Incompatible chemicals  FIRE BEHAVIOUR Fire behavior refers to the specific fire characteristics that occur as a result of the fire's interaction with the environment. Fire behavior characteristics include things like flashover, spotting, rate of spread, and intensity. There are five basic fire behavior principles, and they are: 1. Fire must obey physical laws 2. Where there is fire there is smoke 3. It is the vapor that burns 4. Oxygen increases fire intensity 5. The principle of cooling, smothering and starving  Fire Safety Management Fire Safety Management can be defined as those activities which are undertaken to prevent fires from occurring, the controls that manage fire systems and emergencies and in the event of an uncontrolled fire, the suppression methods used to extinguish it. Fire Safety Management is therefore comprised of three essential elements: 1. Fire Prevention 2. Fire Protection 3. Fire Suppression  Fire Prevention Fire prevention can be defined as those activities that will reduce or eliminate the risk of unplanned fires. Included are things such as:  Fire hazard inspections  Appropriate storage of combustible materials  Fire audits  Disposal of waste flammable materials  Adoption of good housekeeping practices  Conducting fire equipment training  Reporting and correcting fire hazards  Fire Protection Fire protection can be defined as the mechanisms which are established and used to control the application of fire in the workplace. They include such things as: Fire Doors Fire Alarm Systems Smoke Control Systems Fire Resistant Structures Emergency Warning Intercom Systems Emergency Lighting Portable Extinguishers Sprinklers Hydrants  Fire Suppression Fire suppression can be simply defined as stopping the fire. The best method of stopping a fire will vary from situation to situation. It depends largely on the type of fuel involved and the size of the fire itself. Fire suppression involves the effective application of one or more of the four methods of extinguishment, which are: 1. Reducing the heat (Cooling) 2. Removing or reducing the oxygen (Smothering) 3. Removing the fuel (Starvation) 4. Stopping the chemical chain reaction  Extinguishing agents Water: the most commonly used extinguishing agent. Foam: forms blanket therefore denying the fire oxygen and also reduces temperatures Carbon Dioxide: replaces oxygen available to the fire with carbon dioxide. Dry Powder / Chemicals: Variety of different chemicals are used as fire extinguishing agents. They don’t conduct electricity but will smother the fire and assist in breaking the chemical chain reaction. Fire Blankets: work on the principal of smothering; cutting off a fire’s oxygen supply either permanently or, until more effective fire-fighting equipment can be employed.  CLASSIFICATIONS OF FIRES Class A ORDINARY COMBUSTIBLES : These are fires involving such things as wood, paper, fabric and plastic. Class B FLAMMABLE AND COMBUSTIBLE LIQUIDS: Included are flammable liquids such as petrol, solvents and oils. Class C FLAMMABLE GASES: Included are flammable gases such as propane, butane and natural gas Class D COMBUSTIBLE METALS: Included are materials such as magnesium, titanium, and sodium Class E ELECTRICALLY ENERGISED EQUIPMENT : Fires that involve a live electrical source Class K COOKING OILS AND FATS: Involve vegetable oils, animal oils, or fats in cooking appliances Part 2: Storage and Dispensing of Flammable Liquids What is the flammable liquid? Flammable liquids are liquids that have flash points below 37.8°C. Example include solvents such acetone, xylene, ethyl alcohol. The lower the flash and boiling points, the more hazardous the liquid. This greatly impacts the storage restrictions. In order to determine the flash and boiling points of the liquids supplier’s SDS should be consulted.  WHAT THE LAW SAYS? Open regulations for Industrial Establishments, O.Reg. 851/90 and find sections that prescribe storage and dispensing of flammable liquids. Let’s look at the following Let’s discuss key differences terms: between subsection (1), (2), (3)  Immediate use  Sealed containers Can you find another section  Flash point that prescribes dispensing of  Metal cabinet flammable liquids?  Bonding and grounding Precautions to take when storing and dispensing flammable liquids Storing in well ventilated areas to reduce vapour concentrations Free of ignition sources. Separately, away from process and production areas Keeping the amount of materials in storage as small as possible Keep away from incompatible materials Store in cool and dry space Keeping containers closed when not in use Store only in approved containers Supplied with adequate firefighting and spill clean-up equipment. Accessible by firefighters. Dispense from only one container at a time Use only approved transfer pumps and cans Metal containers to be bonded and grounded when dispensing. Eliminate all ignition sources Dispense only in well-ventilated areas. Part 3: Hazards related to Dust and Vapours A combustible dust is any fine material that has the ability to catch fire and explode when mixed with air. When dust is exposed to enough heat or a spark from any ignition source, it can ignite. For a combustible dust explosion to occur, the necessary elements for a fire must be present (fire triangle) and two additional elements: dispersion of dust particles and confinement in a vessel, area, room or building. This is known as Dust Explosion Pentagon How dust explosion occurs When dust is exposed to heat or a spark from any ignition source, it can ignite. Once fine dust particles catch fire while they’re suspended in the air, known as deflagration, it propagates fire, which could lead to rapidly spreading explosion. Video Source: WorkSafeBC Hazard Control Assess the hazard by identifying:  Materials that can become combustible  Processes that use or produce combustible dusts  Open areas where combustible dusts may accumulate  Hidden areas where combustible dusts may accumulate  Means by which dust can be dispersed in the air  Potential ignition sources To mitigate hazards consider the following: o Dust Control o Ignition Control o Damage Control o Maintenance of the dust handling equipment  WHAT THE LAW SAYS? Open regulations for Industrial Establishments, O.Reg. 851/90 and find sections that deals with explosion hazards. Let’s discuss it. 65. (1) Subject to subsection (2), a collector that collects 63. A process that is likely to produce a aluminum, magnesium or other fine dust of an easily ignitable gas, vapour, dust or fume, to such an extent nature shall be located, as to be capable of forming an explosive (a) outdoors; or mixture with air shall be carried out in an (b) in a room used solely for the housing of dust-collecting area which has provision for safe disposal equipment which is, by burning under controlled conditions or in (i) separated from the rest of the building by a dust-tight an area which, partition having a minimum fire-resistance rating of one hour, (a) is isolated from other operations; and (b) has a system of ventilation adequate to (ii) constructed to provide explosion venting to the outdoors. ensure that the gas, vapour, dust or fume (2) Subsection (1) does not apply to a collector, does not reach a hazardous concentration; (a) that uses an inert liquid as a medium to collect dust; (c) has no potential sources of ignition; (b) that is used for a wood-working operation other than wood (d) has provision for explosion venting; and flour manufacturing and having less than 0.47 cubic metres per (e) has, where applicable, baffles, chokes or second capacity; dampers to reduce the effects of any (c) that will safely contain explosions; or explosion. (d) that will resist explosions and is equipped with effective explosion venting to the outdoors. Questions? 29